The Met Office has issued a severe weather warning that thunderstorms and torrential rain could sweep across a wide area that includes Brighton and Hove.
The official forecaster said: “Thunderstorms may develop bringing torrential rain, hail and lightning to a few places, with potential disruption to travel and flooding.”
The warning covers a period from 6pm tomorrow (Tuesday 18 June) to 9pm on Wednesday (19 June).
The warning said: “There is a small chance that homes and businesses could be flooded quickly, with damage to some buildings from floodwater, lightning strikes, hail or strong winds.
“Where flooding or lightning strikes occur, there is a chance of delays and some cancellations to train and bus services.
“Spray and sudden flooding could lead to difficult driving conditions and some road closures.
“There is a slight chance that power cuts could occur and other services to some homes and businesses could be lost.”
The Met Office warned people to “take care when travelling in heavy rain, wind and thunderstorms”.
The forecaster added: “Even moderate rain can reduce your ability to see and be seen. A good rule of thumb is ‘if it’s time for your wipers, it’s time to slow down’.
“If heavy downpours are expected, avoid starting your journey until it clears.
“If you can, choose main roads, where you are less likely to be exposed to fallen branches and debris and flooding.
“Use dipped headlights if visibility is seriously reduced.
“Gusts of wind can unsettle vehicles – grip your steering wheel firmly with both hands. This is particularly important when planning to overtake.
“Keep an eye out for gaps between trees, buildings or bridges over a river or railway – these are some of the places you are more likely to be exposed to side winds.
“Ensure that you maintain enough room either side of your vehicle so you can account for it being blown sideways.
“Roads will be more slippery than usual in wet weather – be sure to give yourself more time to react when approaching a hazard. Increase your following gap to at least four seconds from the moving traffic in front.
“Keep your eyes peeled on the road at all times as spray from other vehicles can suddenly reduce your visibility. Remember it affects others too, so anticipate their actions and be prepared.
“On flooded roads, think before driving through deep water; don’t stop in standing water, and drive through the highest section of the road slowly. If there is any doubt don’t enter it.
“Once you have managed to drive through check your brakes and dry them out as quickly as possible – a light touch of the brakes whilst still moving should do the trick.
“Keep an eye out for cyclists, motorcyclists and pedestrians. Remember to give vulnerable road users including cyclists, motorcyclists and pedestrians more room than usual. They are more likely to be blown around by side winds – always keep a safe distance.”
